Betalains are nitrogenous plant pigments known for their high antioxidant capacity. For the first time, this antioxidant nature has been studied in an in vivo system using the model organism Caenorhabditis elegans. The oxidative stress caused in the fluorescent strain TJ375 (hsp-16.2::GFP) was reversed by the presence of both natural and semi-synthetic betalains, with an ED50 value around 25 μM for betacyanins and up to 10 μM for betaxanthins, with indicaxanthin, the major pigments in prickly pear fruits, as the most effective betalain. The effect of model betalains on the lifespan of the wild-type N2 strain was carefully studied using the automatic platform "Lifespan Machine". In a search for different approaches to suppress progeny, pop-1 RNAi was used to avoid FUdR use. The presence of betalains in the medium, both as pure compounds and as enriched Opuntia extracts significantly increased the lifespan of C. elegans.

Oncosis (from Greek ónkos, meaning “swelling”) is a non-apoptotic cell death process related to energy depletion. In contrast to apoptosis, which is the main form of cell death induced by anticancer drugs, oncosis has been relatively less explored but holds potential to overcome drug resistance phenomena. In this study, we report a novel rationally designed mitochondria-targeted iridium(III) complex (OncoIr3) with advantageous properties as a bioimaging agent. OncoIr3 exhibited potent anticancer activity in vitro against cancer cells and displayed low toxicity to normal dividing cells. Flow cytometry and fluorescence-based assays confirmed an apoptosis-independent mechanism involving energy depletion, mitochondrial dysfunction and cellular swelling that matched with the oncotic process. Furthermore, a Caenorhabditis elegans tumoral model was developed to test this compound in vivo, which allowed us to prove a strong oncosis-derived antitumor activity in animals (with a 41% reduction of tumor area). Indeed, OncoIr3 was non-toxic to the nematodes and extended their mean lifespan by 18%. Altogether, these findings might shed new light on the development of anticancer metallodrugs with non-conventional modes of action such as oncosis, which could be of particular interest for the treatment of apoptosis-resistant cancers. Graphical abstract

Flavonoids are potential nutraceutical compounds present in diary food. They are considered health-promoting compounds and promising drugs for different diseases, such as neurological and inflammatory diseases, diabetes and cancer. Therefore, toxicological and mechanistic studies should be done to assert the biological effects and identify the molecular targets of these compounds. In this work we describe the effects of six structurally-related flavonoids—baicalein, chrysin, scutellarein, 6-hydroxyflavone, 6,7-dihydroxyflavone and 7,8-dihydroxyflavone—on Caenorhabditis elegans’ lifespan and stress resistance. The results showed that chrysin, 6-hydroxyflavone and baicalein prolonged C. elegans’ lifespan by up to 8.5%, 11.8% and 18.6%, respectively. The lifespan extensions caused by these flavonoids are dependent on different signaling pathways. The results suggested that chrysin’s effects are dependent on the insulin signaling pathway via DAF-16/FOXO. Baicalein and 6-hydroxyflavone’s effects are dependent on the SKN-1/Nfr2 pathway. In addition, microarray analysis showed that baicalein downregulates important age-related genes, such as mTOR and PARP.

Betalains are plants pigments identified as potent antioxidant molecules, naturally present in foods like beetroot and prickly pears. Although activities described for betalain-containing formulations include cancer prevention and treatment, the use of extracts instead of purified pigments has avoided the investigation of the real chemopreventive and chemotherapeutic potential of these phytochemicals. Three betalain-rich extracts and six individual pure betalains were used in this work to characterize the activity and to explore possible molecular mechanisms. The animal model Caenorhabditis elegans (tumoral strain JK1466) was used to evaluate the effect of betalains as chemotherapeutics drugs. An objective evaluation method of tumor growth in C. elegans has been developed to assess the possible antitumoral activity of the different treatments. This protocol allowed a fast and reliable screening of possible antitumoral drugs. Among the betalains tested, tryptophan-betaxanthin reduced tumor size by 56.4% and prolonged the animal’s lifespan by 9.3%, indicating high effectiveness and low toxicity. Structure–activity relationships are considered. Assays with mutant strains of C. elegans showed that the mechanism underlying these effects was the modulation of the DAF-16 transcription factor and the insulin signaling pathway. Our results indicate that tryptophan-betaxanthin and related betalains are strong candidates as antitumoral molecules in cancer treatment.

The potential of naturally occurring polyphenols as nutraceuticals to prevent and/or treat Alzheimer's disease is studied. Five structurally related flavones and four tyrosols were tested in vitro in human amyloid-β peptide aggregation assays. The most promising compounds were two flavones, scutellarein and baicalein, and two tyrosols hydroxytyrosol and hydroxytyrosol acetate. These compounds caused a dose-dependent reduction of Aβ-peptide aggregation up to 90% for the flavones and 100% for the tyrosols, at concentrations of 83.3 μM and 33.3 mM, respectively. The IC₅₀ value obtained for scutellarein was 22.5 μM, and was slightly higher for baicalein, 25.9 μM, while for hydroxytyrosol and hydroxytyrosol acetate they were 0.57 mM and 0.62 mM. Given these results, the compounds were selected to conduct in vivo assays with the Caenorhabditis elegans animal model of Alzheimer's disease. The amyloid anti-aggregation ability of these polyphenols was demonstrated in in vivo aggregation assays in which 1 mM hydroxytyrosol reduced the amyloid plaques in the mutant strain CL2331 by 43%. The neuroprotective effect was evaluated in chemotaxis experiments carried out with transgenic strain CL2355 that expresses the human amyloid-β peptide in the neurons. The chemotaxis index was improved by 240% when the neuron-impaired animals were treated with 1 mM hydroxytyrosol. The results indicate that the four molecules would be viable candidates to develop nutraceuticals that interfere in amyloid-β peptide aggregation and, consequently, prevent and/or treat Alzheimer's disease.

trans-α-Methylstilbene (tMS), a resveratrol analogue, has recently been studied in a search for new bioactivities. However, such studies do not take into account that the poor solubility of tMS in aqueous solutions could affect its bioactivity. For this reason, we propose, for the first time, using cyclodextrins (CDs) as solubilizers to increase tMS solubility, in aqueous solutions. The HPLC-RP results obtained, point to a 1 : 1 stoichiometry for all the natural (α-, β- and γ-CD) and modified (HPβCD and MβCD) CDs tested. The K_Fapp (apparent formation constant) for the tMS–CD complexes was seen to be closely dependent on several factors, including the temperature and type of CD. Indeed, the highest K_Fapp value was obtained for MβCD, while the K_Fapp decreased with increasing temperature. In addition, the results showed negative entropy (−8.86 × 10⁻³ ± 0.40 kJ mol⁻¹ K⁻¹) and enthalpy (−16.70 ± 0.98 kJ mol⁻¹) changes and a negative Gibbs free energy value at 25 °C (−14.00 ± 0.55 kJ mol⁻¹) for the encapsulation process. A computational study carried out using molecular docking calculations showed a high degree of correlation between the computed scores and experimental values. Finally, the complexation of trans-stilbene and pinosylvin with HPβCD was compared with tMS.